Ski trimming lock



Sept. 2.3, 1941. w. ARMSTRONG sx1 TRIMMING LooxV Filed Feb. 15, v1940 ssmug-sheet 1 rfvffl. lllllf rlllllll Il." 4 IIIIIII/I/ G mm www rn m WM7 M nh M w Vl Sept. 23,V 1941. w. ARMSTRONG SKI T RIMMING LOCK FiledFeb. l5, 1940 3 Sheets-Sheet 2 Sept. 23, 1941. I w. ARMSTRONG A Y SKITRIMMING LOCK Filed Feb. 15, 1940 3 Sheets-Sheet 3 n y V Patented Sept.23, 1941 SKI TRIMMING LOCK William Armstrong, New York, N. Y., assignorto The Dowty Corporation, Wilmington, Del., a corporation of DelawareApplication February 15, 1940, Serial No. 319,073

A 2,256,541 UNITED STATES PATENToFFIcE 6 Claims.

This invention relates to a ski trimming lock and more particularly tosuch a lock on -a ski which is mounted on the airplane with what isknown as levered suspension.

The principal object of the present invention is to provide a skitrimming lock controlled by compression and extension of the suspendinglever upon which the ski is pivotally mounted; when 4the lever iscompressed under the weight of the airplane upon the ski, the lockingmeans is automatically unlocked so that the ski is free to pivot Whilethe airplane is on the ground. When the airplane takes off, theextension of the lever of the lever suspension automatically causeslocking of the ski in a predetermined position parallel to the plane offlight.

Another object is to provide a ski lock of the foregoing type whereinwhat is known as parallel leverage suspension of the ski is employed.

Another object is to provide a ski trimming lock of the foregoing typewhich is simple to construct, inexpensive to manufacture, light inweight, which presents a minimum of air resistance, which is inexpensiveto maintain, and which operates very eiectively to positively lock theski against iiuttering or pivoting during flight and automaticallyunlocks the ski for free pivotal movement upon engagement of theairplane with the earth, said pivotal movement being restrained withinlimits.

Other objects of the present invention will more fully hereinafterappear.

Reference is made to my copending applications, Serial Nos. 319,072 ledFeb. 12, 1940, and 319,074, led Feb. 15, 1940, which disclose skitrimming locks embodying principles related to the present application.

In the accompanying drawings: y

Fig. 1 is a side elevation of an airplane equipped with a leveragesuspension ski provided with one'form of locking device embodying theprinciples of the present invention. This ligure shows the airplane onthe ground with its tail down.

Fig. 2 is a fragmentary vertical section of the locking mechanism ofFig. 1. This view shows the ski locked, the airplane being in flight.

Fig. 3 is a similar View showing the device when the airplane is on theground with the tail up and there is no deflection-oi the ski relativeto the surface of the ground.

Fig. 4 is a side elevation of the device of Figs. 1 to 3 showing it asthe airplane is on vthe ground with the tail down and with no deflectionof the ski.

Fig. 5 is a rear View of Fig. 4.

Fig. 6 is a View similar to Fig. 4 showing the device with the tail downand with the ski tilted so as to elevate its front end. This view may beconstrued as illustrating an airplane taking off and Vencountering anobstruction in the surface of the earth whichthrows the front end of theski upwardly.

Figs. 7 and 8 portray aA modification, Fig.A 7 showing the modied formwith the ski locked in flight and Fig-8 showing it in unlockedpositionwith the tail of the airplane down.

Figs. 9 and 10 portray another modification in which what is known asparallel levered suspension of the skiis employed. In these views, Fig.9 shows the mechanism locked in flight and Fig. l0 shows the mechanismasl it appears when the airplane is on the ground with the tail down andwith no deflection of the ski.

Figs. 11 and 12 portray still another modification in which .parallellever suspension is used.

4In these views, Fig. 11 shows lthe device `locked in flight while Fig.12 shows the device .unlocked with the airplane on the ground With'itstail down and with no deflection of the ski.'y

Referring to thev drawings in detail and-to the embodiment illustratedin Figs. 1 to 6,. I designates the body of an airplane having a wing 2from which there depends a iixed strut 3.. No attempt is made toillustrate the-construction of the strut 3 other than diagrammaticallysince its construction is Well within the skill of the art, it beingsuiiicient to state that the strut 3 is carried by the airplane anddepends downwardly therefrom. Strut 3-may be rigidly carried by theairplane or yieldingly or pivotally mounted thereon. At the lowerV endof strut 3, there is pivotally mounted the rearwardly extending lever 4which is adapted to swing up and down relative to strut 3. yPivotallymounted on the rearwardend of lever. 4 is the ski 5 which has thepedestal Ei which is pivotally engaged with the rear end of lever 4, asby means oi' the pivot pin 1.

Arranged between strutl 3 and lever 4 is a shock absorber, one form ofwhich is diagrammatically illustrated as comprising the cylinder 8 xedlycarried in the lower end of strut 43, the spring 9 and the piston I0having the port I'I which is adapted to allow .air under pressure topass from above piston I 0 to a point therebelow. vFixedly carried bythe piston I0 is rod I2 which extends downwardly intopivotedrelationship with lever 4 by means of a pivot pin I3.

The ski locking device comprises the locking pin I4 rigidly carried bythe rearwardly extending ears I5 which are rigidly mounted' in anysuitable manner upon the exterior of strut 3. Cooperatively associatedwith the locking pinV I4 are the upwardly extending locking plates I6which are rigidly secured to the ski 5 in any desired manner, as forexample by welding to the pedestal 6. The locking pin I4 is receivedwthin the slot or opening in the locking plates The opening in thelocking plates I6 is designed to allow considerable pivotal movement ofthe ski relative tothe 'strut 3 whenthe weight of the airplane isf onthe ski, and to automatically lock these elements against relativepivotal movement when the airplane leaves the earth. The j openingY hastheV relatively wide portion extendportion I9. Y Y the rear guide wallwhichv is shown as taking Y ingV between the `points I1 and I8 andthe/locking- Points I8 and I9 areuconnected-by 10' the form of astraight line extending between Y points I8 and I9 but which obviouslyymay beV curved or arcuate provided it is of sucha configuration as toguide the pin I4 along it into they lockingspace I9.l rllfhe points `I1and I9 are connected-by theupperf'front'wall 2l which comprisesthe'upwardly curved portion' `23 ywhich leads to the inwardly curvedshoulderportion 22c'losely dent'theglockipg portion 1 I9. and which is'adapted' to similarly guide pin |14 into [portionle per. Wall 2Imay'fbe'a "straight line similar to the lupperiwaljll, t.

'p e for reception of thej pinjl in c ase an un- ."usually violent.shockis encountered in takingv oil "orlanding. Asshownrjthel'ovvor'portion of the comprises theflowerf straight -rear wall 24, and

lowerflarcuate frontjwall 2 5', tliese being coned throughStheintermediary of the porfflll'v'? -Y 'l The',provisioniof the .convexcurve 2 3 followed bythe concavepoirtion22 .causes vthe locking pin ,I4Whichisnormal1y moving around in the forfyvyahaifoftne' rocking.slotdurfng taking, on to v belmoved intothelocking portion l'with a.snap "as' i`t. passes over shoulder 22.

be obvious from theforegoing and from the draw- :irigsliutmayfbes'tatedbrie'y as follows: n". .Upon'elevatmg the tail of the airplane prepar-.atory to' oifthejpartsassume the position ,showhirLl-'igoj; the`\.'vveight ylof the airplane hav-` `igkompif`sS`ed the springl 9 of theshock absorber havingoaus'edthereby the' locking pin I4 toY"Inojiedov'vn'vvardly intdsubstantially the widest Yportion of theslot. VDuring the take-o, the ski is free to move through an angle of'atleast 15 finf'eitheri direction about its pivot point. Should.anfobstriictionbeencountered during the take-01T .which calulsesAtlegfrontof the 'skiY to rise, the locking plate ljwill 'be turned'.soas 'to move the pla/[41mm the forwardhaif ofthasiot. As the i is'.completed, the 'looking pin I4 has .Inoved'upwardly soasfto' engageone'jof'the suru'fa'ce's'eZUQor. 2l enclbe. guided thereby into thelockirigfportion I' by rreason yof the'expan'si'on of y.th 's'pring9-lotfthe, shlock absorber.

l the'tailjdown, the pin willmove linfa fc'urved'pathto the4 positionshow n in Fig. 4. l'It the landing iswithithe tail up, yit yWill move tot Ae positi'orrshown inlign 3. Thereafter, it will @riiefe' around inthefslot allowing the skit@ pivot freely within limits set by thesidesof the slot T 'Iponlflandrgjwhen. .the skis engage :the

so as to accommodate itself to the terrain during the landing. l i t.

y I .JAY-4l Modification ofyEigurs 7i and 8v In Figs. '7 and 8, there isshown amodication of the embodiment of Figs. 1 to 6. VIn themodifiedform of the device, the only difference is that the location ofthe locking plate and of the locking pin is interchanged, the lockingplate 21 be- `Ving rigidly mounted on the side of the strut 3 and'tlf-lie pin 23'being rigidly mounted between two vears 29 which arerigidly mounted upon or in-V tegral with the pedestal 6 of the ski 5.The slot inthe locking plate 21 comprises the locking portion 39,. theslanting front wall 3l and the slantingr-front wall 3-2. The wall'3'Iifs'adapted'tov engage ,the pi-n2S- when the rear-of the ski is ele# vvva'ted while the wall32'which has a greater angle I to allow forsuicient freedom-'of movement when the'tail is'down is adapted toengage'th pin 2'8 when the front of the ski is elevated. The'slant-'in-gl Walls BIV'and 32 cooperate with the locking recess- 530 tovguideY the locking pin 23'into this recessl when take-off has beencompleted. The upper relatively YWide'portion oftheslot com- 'pr'isestheareuatewalls 3,3fan'd 34 and-'the flat connectingportion 3.5.A It willbe apparent that the portionfof the slotwhich isv occupiedjohiey by thevpin 28 wilflbe that portion lyingbetween points A36'ai1d431'. TheYoperation of the device" is Ythe same as thatior the embodiment shownin Figs. 1 to `6. Y

Modification' f Figures 9 to ,12

Zcurved portion 4I and the strutv 3:8',- thi's shock'ab- Y sorbercomprising the barrel 42 which is pivotally mounted to the strut 38 at43. The shock ab- ;sorber =also comprises' the telescoping rod` 44 whichengages mechanism not shown within the barrel 42'Which is vadapted to`y-ieldingly allow compressionof rod' 44 Within barrel 42 and tonormally urge rod 44 Arearwardly'out of barrel 42. The rod 44 is pivotedtothe'u'pper end of the rear tipv 4I of lever'39'as' at 45.

`Describing vrno'W'the locking device of Figs. 9 andy 101, thiscomprises the lockingplates 4t rwhich are rigidly mounted on the ski/5as by welding vto the pedestal 6. The locking device further comprisesthe pins41 which extend laterally on each side of the barrel I2I andwhich are rigidly Ycarried by the barrel 4-2. VThe slot in the lockingplate 46 is designed as before With a locking recess48- and with guideWalls '4-9 and 50 which converge into the locking portion 48. Theoperation of the device is essentially the same as the operation of thedevice shown in'Fig's., 1 tov 6, the guide Walls 49 and Sil'fserving toguidel the pin 41 'into the locking recess 48y and the relatively Wideportion below the guide. walls 4@ rand 5D serving to .accomkInodatethepin 41V during 'landing and take-01T.

In Figs. 11and l2, the disposition of the locking plate andv the lockingpin is reversedfthe being rigidly carried by the ski 5 by means of theears 53 which are integral with the pedestal 6. The pin 52 is adapted tobe held within a locking portion 54 of the slot in plate 5l. The pin 52is adapted to be guided into this locked position by the guide walls 55and 5i; which converge into the locking portion 5d. The operation isidentical with that described for Figs. 9 and 10.

From the foregoing, it will be seen that the present invention providesa locking device which is economical to build, simple in operation andlight in weight. The device operates positively and reliably to lock andunlock the ski as take-off and landing occur. The device oners a minimumof air resistance although if desired fairing of any suitable type maybe provided around the device.

I wish it to be understood that I intend to include as within theinvention such modincaend of said lever, shock absorber means interposedbetween said strut and said lever and tending normally to move saidlever and thereby said ski downwardly, and a trimming lock for said ski,said lock comprising a slotted locking plate member and a cooperatinglocking pin .Y

member received in the slot in said plate, the slot in said plate memberhaving a locking portion adapted to receive said pin member and tothereby lock said ski, one of said locking members being carried by saidstrut and the other ,f

of said locking members being rigidly carried by said ski.

2. In an airplane landing gear, a downwardly extending strut carried bythe airplane, a lever pivotally mounted at one end to said strut, a skipivotally mounted on the other end of said lever, shock absorber meansinterposed between said strut and said lever and tending normally tomove said lever and thereby said ski downwardly, locking means forlocking said ski in night comprising a slotted locking plate member anda locking pin member received in the slot in said plate, one of saidmembers being carried on said strut and the other of said members beingrigidly carried on said ski, said slot comprising a relatively wideportion adapted to receive said pin member and allow relatively greatpivoting of said ski when the weight of the airplane is on the ski, arelatively narrow locking portion adapted to lockingly receive said pinmember when the airplane is in flight, and side walls converging fromsaid wide portion to said locking portion for guiding said pin memberinto said locking portion as the airplane takes on.

3. In an airplane landing gear, a strut carried by the airplane andextending downwardly therefrom, a lever pivotally mounted at one end onsaid strut, a ski pivotally carried by said lever, shock absorber meanscarried between said lever and said strut, and locking means for lockingsaid ski comprising a slotted locking plate carried by said strut and acooperating locking pin rigidly carried by said ski and received withinthe slot of said plate, said slot comprising a relatively wide portionadapted to accommodate said pin freely within limits when the weight ofthe airplane is on the ski, a relatively` small locking portion adaptedto lockingly receive said pin when the airplane is in flight, andinclined side walls converging from said wide portion to said lockingportion for guiding said pin to said locking portion as the airplaneleaves the earth.

4. In an airplane landing gear, a strut oarried by the airplane anddepending downwardly therefrom, a lever pivotally mounted at one end tosaid strut and adapted normally to lie at an angle thereto, shockabsorber means interposed between said strut and said lever and normallytending to urge said lever downwardly, a ski pivotally mounted on theother end of said lever, and locking means for said ski comprising aslotted locking plate rigidly carried on said ski and a locking pincarried by said strut and received in the slot in said plate, said slotin said plate having a locking portion on the side thereof away fromsaid ski and side walls converging away from said ski towards and intosaid locking portion for guiding said pin into said locking portion asthe airplane leaves the earth.

5. In an airplane landing gear, a strut carried by the airplane, a leverpivotally mounted at one end on the lower end of said strut, a skipivotally mounted on the other end of said lever, a shock absorbertelescopically associated with said strut and interposed between saidstrut and said lever, and means for locking said ski in night comprisinga slotted locking plate member and a locking pin member received in theslot of said plate member, one of said members being rigidly mounted onsaid strut and the other of said members being rigidly mounted on saidski, the slot in said plate having a relatively wide portion and anarrow locking portion and having sides gradually converging from saidrelatively wide portion to form said narrow portion.

6. In an airplane landing gear, a strut depending from the airplane, alever pivotally mounted thereon and adapted to normally lie at an anglethereto, a ski pivotally mounted on the other end of said lever, shockabsorber means extending generally parallel to said lever and having oneof its elements pivotally connected to said strut and the other of itselements pivotally connected to said lever, said shock absorber normallytending to move its elements apart, and locking means for locking saidski in night comprising a slotted locking plate member and a locking pinmember in the slot of said plate member, one of said members beingrigidly carried by said element connected to said strut and the other ofsaid members being rigidly carried by said ski, said slot comprising arelatively wide portion adapted to accommodate said pin member when theweight of the airplane is on the ski within relatively great limits offreedom, a locking portion on the side away from the member on whichsaid plate member is carried, and converging side walls leading fromsaidwide portion to said locking portion.

WILLIAM ARMSTRONG.

